Visual Acuity and Quality of Life Outcomes in Cataract Surgery Patients in Hong Kong Joseph Lau, John J Michon, Wing-Shing Chan, Leon B Ellwein

WORLD VIEW Br J Ophthalmol: first published as 10.1136/bjo.86.1.12 on 1 January 2002. Downloaded from Visual acuity and quality of life outcomes in cataract surgery patients in Hong Kong Joseph Lau, John J Michon, Wing-Shing Chan, Leon B Ellwein ......

Br J Ophthalmol 2002;86:12–17

Series editors: Background: Visual acuity, visual functioning, and vision related quality of life outcomes after cataract W V Good and S Ruit surgery were assessed in a population based study in a suburban area of Hong Kong. Methods: A cluster sampling design was used to select apartment buildings within housing estates for enumeration. All enumerated residents 60 years of age or over were invited for an eye examination and visual acuity measurement at a site within each estate. Visual functioning (VF) and vision related quality of life (QOL) questionnaires were administered to interview subjects who had undergone cataract surgery and to unoperated people with presenting visual acuity less than 6/60 in either eye, and a sample of those with normal visual acuity. Results: 36.6% of the 310 cataract operated individuals had presenting visual acuity 6/18 or better in both eyes, and 40.0% when measured by pinhole. 4.5% were blind, with presenting visual acuity less than 6/60 in both eyes. Of operated eyes, 59.6% presented with visual acuity 6/18 or better. 11.2% of the operated eyes were blind with vision less than 6/60. Visual acuity outcomes 6/18 or better were marginally associated with surgery in private versus public hospitals. Lens status (pseudophakic versus aphakic) and surgical period (within the most recent 3 years versus before) were not significantly related to vision outcomes. Mean VF and QOL scores decreased consistently with decreasing See end of article for authors’ affiliations vision status. Spearman correlation with vision status was 0.420 for VF scores and 0.313 for QOL ...... scores. Among VF/QOL subscales, correlation was strongest for visual perception (r = 0.447) among VF subscales and weakest for self care (r = 0.171) among QOL subscales. Regression adjusted VF and Correspondence to: QOL total scores for cataract operated individuals were slightly lower than for those of visually com- Leon B Ellwein, PhD, National Eye Institute, 31 parable unoperated individuals (p<0.05). Center Drive, Bethesda, Conclusions: Cataract operations in Hong Kong did not consistently produce good presenting visual MD 20892–2510, USA acuity outcomes, suggesting that postoperative monitoring would be useful to minimise visual impair- Accepted for publication ment in this population. Although vision outcomes were consistently correlated with all VF/QOL 23 July 2001 subscale scores, there was a differential impact with VF subscales usually being affected more by

...... reduced acuity than the more general QOL subscales. http://bjo.bmj.com/

ataract was found to be leading cause of blindness in sented public, private, and home ownership scheme (govern- individual eyes with presenting visual acuity less than ment subsidised self purchased) housing. 6/60 among people aged 60 or older in Hong Kong.1 In In door to door enumeration, 4487 eligible subjects 60 years C 23 recent population based studies in rural China and other of age or older were identified, of which 3441 (76.7%) 45 studies in Western countries, advanced age was found to be completed visual acuity measurement and an ocular examina- on September 30, 2021 by guest. Protected copyright. the most important factor associated with the development of tion at a temporary site set up within the neighbourhood. cataract and subsequent vision impairment. As the Hong Cataract operated individuals were queried as to the date and Kong population ages, morbidity associated with cataract sur- hospital where their surgery was performed. Further details gery is expected to rise. In planning medical services for cata- regarding the sampling and examination methods are ract patients, it is essential to include the assessment of post- reported in a companion paper.1 surgical outcomes not only in terms of visual acuity, but also Visual functioning (VF) and vision related quality of life for patient self reported visual functioning and vision related (QOL) interviews were conducted in those who had cataract quality of life. surgery, in those presenting with visual acuity worse than 6/60 This article presents findings on visual acuity, visual in either eye, and in approximately 5% of unoperated people functioning, and quality of life outcomes in a population with visual acuity >6/18 in both eyes. based, cross sectional sample of elderly Hong Kong Chinese with operated cataract in one or both eyes. Because a similar VF and QOL instruments protocol was employed, the results presented here can be The VF/QOL questionnaires used in this study were originally compared directly with findings from two studies in mainland developed for a large scale clinical trial of cataract surgery in China,67where the socioeconomic and medical service condi- India.89 Both questionnaires have been successfully used in tions differ substantially. surveys of blindness and cataract outcomes in Nepal10 and in the Shunyi6 and Doumen7 districts of China. A translation of METHODS the original English version into Cantonese, the local Chinese Sample and design dialect, was used.7 The study was conducted in the Shatin area of Hong Kong. In The VF instrument consists of 12 items in four vision this densely populated suburban area, large apartment build- subscales—visual perception (activity limitation, near vision, ings comprise 95.0% of all housing. Cluster sampling was used intermediate vision, and distance vision), sensory adaptation to select subjects living in 30 representative apartment build- (light/dark adaptation, visual search, colour discrimination, ings from 15 large housing estates. The 15 estate strata repre- and glare disability), peripheral vision (single item), and

www.bjophthalmol.com Visual acuity and quality of life outcomes in cataract surgery patients in Hong Kong 13

depth perception (single item). The QOL instrument contains 6/18 with procedure type, surgery period, and hospital type Br J Ophthalmol: first published as 10.1136/bjo.86.1.12 on 1 January 2002. Downloaded from 12 items, comprising four subscales—self care (bathing, was investigated by multiple logistic regression for operated eating, dressing, and toileting), mobility (walking to neigh- eyes. Associations between vision status and VF/QOL scores bours, walking to shops, and doing household chores), social were assessed by Spearman correlation coefficients. Differ- interaction (attending functions and meeting friends), and ences in VF/QOL scores between aphakic and pseudophakic mental wellbeing (burden on others, dejection, and loss of individuals were assessed by linear regression adjusted for confidence). Both questionnaires assess the current degree of demographic variables. Regression analyses were also used to difficulty being experienced by the subject on a four point compare the VF and QOL scores between operated and unop- scale from “not at all” to “a lot.” Subscale scores are linearly erated individuals using vision status and demographic transformed so that the response range is between 0 and 100. variables as control variables. Composite scores for VF (VF Total) and QOL (QOL Total) instruments were calculated by equal weighting of subscale scores. RESULTS Interviewers were trained in general interviewing tech- A cross sectional sample of 310 Hong Kong Chinese aged 60 niques and administration of the questionnaire through the years or older who had cataract surgery in one or both eyes, use of a master interviewing audiotape. Practice interviews some of whom had been operated on decades earlier, were were conducted on both outpatients and inpatients (none of identified. Most of them (64.8%) had no formal education, them were study subjects) at the Hong Kong Eye Hospital and 69.0% were female, 75.4% were 70 years of age or more, and Queen Mary Hospital in Hong Kong. Fifty three additional 51.6% lived in public housing estates. Fifty three per cent had subjects were interviewed in a pilot study in Shatin conducted bilateral cataract operations. There were 273 (88.1%) pseudo- before the main study. Intraobserver and interobserver agree- phakes, 34 (11.0%) aphakes, and three individuals with unde- ment of VF/QOL questionnaire responses were evaluated in 28 termined lens status. (None of the cases was aphakic in one of the study subjects. Repeat interviews were conducted eye and pseudophakic in the other.) approximately 1 hour after the initial one. A weighted kappa statistic was used to assess the degree of agreement across the Visual acuity outcomes original 4 point rating scale of each VF/QOL item. Weights Table 1 shows presenting visual acuity status for cataract were 1.0 for exact agreement and 0.66, 0.33, and 0.0, operated individuals. The percentage of subjects with normal/ respectively for disagreement of 1, 2, and 3 points. Kappas for near normal acuity was 36.6%, while 4.5% had visual acuity intraobserver agreement (n = 12) were between 0.55 and 1.00 less than 6/60 in both eyes. Considering only better eye vision, for VF items and between 0.67 and 1.00 for QOL items. Inter- 71.2% had normal or near normal acuity. observer agreement (n = 16) ranged between 0.52 to 0.87 for Pseudophakes were more likely to have normal/near VF items and, except for one item, between 0.56 and 1.00 for normal acuity than aphakes; 40.1% (109/272) of the QOL items. Internal consistency of responses for the 12 items pseudophakes and 88.2% (30/34) of the aphakes wore specta- in the VF scales as measured by Cronbach’s alpha was 0.87 cles for distance correction. With pinhole measurement, the (average inter-item correlation coefficient = 0.36), and for the number of subjects with normal/near normal acuity increased 12 items in the QOL scale it was 0.89 (average inter-item cor- from 113 (36.6%) to 124 (40.0%) and the number of bilaterally relation coefficient = 0.41). The alpha values for the VF and blind (moderate plus severe blindness) decreased from 14 QOL subscales ranged from 0.74 to 0.87 and 0.82 to 0.89 (4.5%) to 12 (3.9%) (data not shown). respectively. Table 2 shows visual acuity for aphakic and pseudophakic http://bjo.bmj.com/ eyes: overall, 59.6% of eyes had presenting visual acuity of 6/18 Data analysis or better, 29.2% were between less than 6/18 and 6/60, while Vision status at the person level was defined using five catego- 11.2% had acuity worse than 6/60. When measured by pinhole ries: (1) normal or near normal vision: 6/18 or better in both visual acuity, 42.8% of the operated eyes with presenting eyes; (2) unilateral or bilateral visual impairment: worse than visual acuity between less than 6/18 and 6/60 increased to 6/18 to 6/60 or better in worse eye, 6/60 or better in better eye; acuity of 6/18 or greater; and 16.9% with presenting visual (3) unilateral blindness: worse than 6/60 in worse eye, 6/60 or acuity below 6/60 increased to acuity between less than 6/18 to on September 30, 2021 by guest. Protected copyright. better in better eye; (4) moderate bilateral blindness: worse 6/60 or greater (none increased to >6/18). Accordingly, the than 6/60 in worse eye, less than 6/60 to 3/60 or better in bet- overall percentages of operated eyes with pinhole visual acuity ter eye; and (5) severe bilateral blindness: worse than 3/60 in of 6/18 or greater, less than 6/18 to 6/60, and below 6/60 were both eyes. 72.1%, 18.6%, and 9.3%, respectively. Pseudophakic eyes had Statistical analyses were performed with appropriate better vision than aphakic eyes with both presenting and pin- adjustments for the cluster and stratified sample design.11 The hole visual acuity. In particular, 23.7% of aphakic eyes association of presenting visual acuity greater than or equal to presented with visual acuity less than 3/60, compared to 5.4%

Table 1 Presenting vision of individuals

Better eye vision acuity No (%) of individuals

Vision category >6/18 <6/18 to >6/60 <6/60 to >3/60 <3/60 Total

Normal/near normal (>6/18 both eyes) 113 (100.0) 0 (0.0) 0 (0.0) 0 (0.0) 113 (36.6) Visual impairment (>6/60 better eye, <6/18 to >6/60 worse eye) 73 (62.4) 44 (37.6) 0 (0.0) 0 (0.0) 117 (37.9) Unilateral blindness (>6/60 better eye, <6/60 worse eye) 34 (52.3) 31 (47.7) 0 (0.0) 0 (0.0) 65 (21.0) Moderate blindness (<6/60 to >3/60 better eye, <6/60 worse eye) 0 (0.0) 0 (0.0) 9 (100.0) 0 (0.0) 9 (2.9) Severe blindness (<3/60 both eyes) 0 (0.0) 0 (0.0) 0 (0.0) 5 (100.0) 5 (1.6) All 220 (71.2) 75 (24.3) 9 (2.9) 5 (1.6) 309 (100.0)*

*Does not include one pseudophakic person with missing visual acuity.

www.bjophthalmol.com 14 Lau, Michon, Chan, et al Br J Ophthalmol: first published as 10.1136/bjo.86.1.12 on 1 January 2002. Downloaded from Table 2 Presenting visual acuity and pinhole visual acuity in eyes operated for cataract*

Pinhole visual acuity

Presenting visual acuity >6/18 <6/18 to >6/60 <6/60 to >3/60 <3/60 Total

>6/18 Aphakic 28 (100.0) 0 (0.0) 0 (0.0) 0 (0.0) 28 (47.5) Pseudophakic 254 (100.0) 0 (0.0) 0 (0.0) 0 (0.0) 254 (62.0) <6/18 to >6/60 Aphakic 3 (14.0) 11 (78.6) 0 (0.0) 0 (0.0) 14 (23.7) Pseudophakic 56 (45.2) 68 (54.8) 0 (0.0) 0 (0.0) 124 (30.2) <6/60 to >3/60 Aphakic 0 (0.0) 1 (33.3) 2 (66.7) 0 (0.0) 3 (5.1) Pseudophakic 0 (0.0) 4 (40.0) 6 (60.0) 0 (0.0) 10 (2.4) <3/60 Aphakic 0 (0.0) 2 (14.3) 0 (0.0) 12 (85.7) 14 (23.7) Pseudophakic 0 (0.0) 2 (9.1) 1 (4.5) 19 (86.4) 22 (5.4) Undetermined† 0 (0.0) 0 (0.0) 0 (0.0) 4 (100.0) 4 (100.0) All Aphakic 31 (52.5) 14 (23.7) 2 (3.4) 12 (20.3) 59 (100.0) Pseudophakic 310 (75.6) 74 (18.0) 7 (1.7) 19 (4.6) 410 (100.0)‡ Undetermined† 0 (0.0) 0 (0.0) 0 (0.0) 4 (100.0) 4 (100.0)

*Data are presented as number (%) of eyes; †undetermined lens status due to corneal opacity or phthisical/absent globe; ‡does not include one pseudophakic eye with missing visual acuity. of pseudophakic eyes, with neither group improving much explanatory variables, and with further adjustments for hous- with pinhole correction. ing, sex, age, and education level. Operations performed in foreign countries were excluded in the analysis because of Cause of vision impairment their small number. Regression results showed that neither Table 3 gives the principal cause of vision impairment or surgical period nor lens status was significantly associated blindness for 31 of 59 aphakic eyes and 156 of 411 with presenting visual acuity 6/18 or greater (p = 0.804 and p pseudophakic eyes with presenting visual acuity less than = 0.208). The better outcomes in private hospitals were of only 6/18, as well as the four eyes with undetermined lens status. marginal significance (adjusted odds ratio = 1.84, p = 0.067). Refractive error (34.6%), age related macular degeneration The cataract operated between the ages of 60 to 69 were found (18.3%), glaucoma (10.5%), and posterior capsule opacity to have better outcomes than those aged 80 or more (adjusted (8.4%) were the four leading causes of visual acuity loss. The odds ratio = 2.36, p = 0.016). Housing type, sex, and causes of visual loss were somewhat different between apha- education level were not associated with vision outcomes. The kic and pseudophakic eyes: the leading causes in aphakic eyes interaction between age and surgical period in the regression were non-glaucomatous optic atrophy (22.6%), glaucoma model was examined and was found to be non-significant. (19.4%), and refractive error (12.9%), while in pseudophakic eyes the principal causes were refractive error (39.7%), macu- VF and QOL outcomes http://bjo.bmj.com/ lar degeneration (20.5%), and posterior capsule opacity VF and QOL interviews were successfully completed in 299 (10.3%). (96.5%) of the 310 aphakic/pseudophakic individuals, and in 237 (96.3%) of 246 unoperated individuals with presenting Surgical variables visual acuity less than 6/60 in one or both eyes. Also, 87 unop- Presenting visual acuity of operated eyes stratified by period of erated individuals with normal/near normal visual acuity had surgery, hospital type, and lens status is shown in Table 4. For VF/QOL interviews.

bilaterally operated people, only the ﬁrst operated eye is Mean VF and QOL scores by presenting vision outcome for on September 30, 2021 by guest. Protected copyright. shown. Second operated eyes were not included to maintain cataract operated individuals are shown in Table 5. Increasing independence among eyes in statistical analyses.12 vision impairment was correlated with older age (Spearman Visual acuity outcomes >6/18 were investigated using a correlation = 0.157, p = 0.007); housing, sex, and education multiple logistic regression model with surgical period, type of were not. Mean scores decreased consistently across total VF hospital, and lens status incorporated simultaneously as and VF subscales with decreasing vision status, as evidenced

Table 3 Principal causes of impaired vision in operated eyes with presenting acuity less than 6/18

No (%) of eyes with visual acuity <6/18

Principal cause Aphakics Pseudophakics Undetermined* Total

Refractive error 4 (12.9) 62 (39.7) 0 (0.0) 66 (34.6) Macular degeneration 3 (9.7) 32 (20.5) 0 (0.0) 35 (18.3) Glaucoma 6 (19.4) 14 (9.0) 0 (0.0) 20 (10.5) PCO/after cataract 0 (0.0) 16 (10.3) 0 (0.0) 16 (8.4) Optic atrophy 7 (22.6) 4 (2.6) 0 (0.0) 11 (5.8) Diabetic/vascular retinopathy 2 (6.5) 8 (5.1) 0 (0.0) 10 (5.2) Corneal opacity 1 (3.2) 7 (4.5) 1 (25.0) 9 (4.7) High myopia 3 (9.7) 4 (2.6) 0 (0.0) 7 (3.7) Phthisical/absent globe 1 (3.2) 1 (0.6) 3 (75.0) 5 (2.6) Retinal detachment 2 (6.5) 2 (1.3) 0 (0.0) 4 (2.1) Other/undetermined 2 (6.4) 6 (3.8) 0 (0.0) 8 (4.1) All 31 (100.0) 156 (100.0) 4 (100.0) 191 (100.0)

*Undetermined lens status due to corneal opacity or phthisical/absent globe.

www.bjophthalmol.com Visual acuity and quality of life outcomes in cataract surgery patients in Hong Kong 15 Br J Ophthalmol: first published as 10.1136/bjo.86.1.12 on 1 January 2002. Downloaded from Table 4 Presenting visual acuity of first operated eyes and association of surgery period, type of hospital, and lens status with visual acuity >6/18

Visual acuity Adjusted odds ratio* >6/18 <6/18 to >6/60 <6/60 All (95% CI) p Value

Surgery period <3 years 89 (60.1) 47 (31.8) 12 (8.1) 148 0.93 (0.54 to 1.59) 0.804 >3 years 86 (56.6) 42 (27.6) 24 (15.8) 152 1.00 Missing 5 4 0 9 Type of hospital Public 74 (51.4) 48 (33.3) 22 (15.3) 144 1.00 Private 94 (65.7) 42 (29.4) 7 (4.9) 143 1.84 (0.95 to 3.58) 0.067 Foreign country 11 (61.1) 2 (11.1) 5 (27.8) 18 Missing 1 1 2 4 Lens status Aphakic 14 (40.0) 10 (28.6) 11 (31.4) 35 1.00 Pseudophakic 166 (61.5) 83 (30.7) 21 (7.8) 270 1.99 (0.66 to 5.99) 0.208 Undetermined 0 0 4 4 All 180 (58.3) 93 (30.1) 36 (11.7) 309

*Includes adjustment for housing type, sex, age, education, as well as surgery period, type of hospital, and lens status in a multiple logistic regression model with presenting visual acuity >6/18 as the outcome variable.

Table 5 Visual function and quality of life mean scores (and standard errors) for individuals operated on for cataract by presenting vision status

Vision status

Mod/severe Vision Unilateral bilateral Normal impairment blindness blindness Spearman correlation Demographic variables (n=110) (n=114) (n=62) (n=13) All (n=299) coefficient (95% CI)

% Public housing 50.0 51.8 51.6 53.8 51.2 % No education 65.5 64.0 64.5 61.5 64.5 % Male 26.4 35.1 37.1 15.4 31.4 Mean age (years) 74.0 75.4 76.5 77.9 75.2 VF scales Visual perception 91.0 (1.2) 81.6 (1.1) 70.3 (4.0) 46.9 (7.9) 81.2 (1.0) 0.447 (0.351 to 0.533) Peripheral vision 89.8 (1.5) 84.8 (1.6) 69.6 (5.5) 55.8 (12.9) 82.2 (1.2) 0.292 (0.185 to 0.392) Sensory adaptation 78.4 (1.4) 69.5 (1.8) 61.9 (2.9) 39.5 (6.5) 69.9 (1.4) 0.380 (0.279 to 0.473) Depth perception 93.0 (1.9) 89.9 (1.5) 80.6 (3.0) 54.8 (8.9) 87.6 (1.1) 0.290 (0.183 to 0.391)

Total VF 88.0 (1.2) 81.5 (1.1) 71.2 (2.9) 49.2 (7.9) 80.4 (0.8) 0.420 (0.322 to 0.509) http://bjo.bmj.com/ QOL scales Self care 97.9 (0.7) 98.9 (0.4) 94.2 (1.8) 96.2 (1.3) 97.4 (0.4) 0.171 (0.059 to 0.279) Mobility 94.9 (1.2) 92.3 (1.4) 84.6 (3.0) 68.1 (11.2) 90.6 (0.9) 0.249 (0.140 to 0.352) Social 91.3 (1.6) 89.2 (2.2) 81.9 (3.6) 62.6 (10.2) 87.3 (1.6) 0.208 (0.097 to 0.314) Mental 89.9 (1.5) 80.3 (1.9) 68.2 (5.0) 65.1 (8.6) 80.6 (1.9) 0.293 (0.186 to 0.393) Total QOL 93.5 (0.9) 90.6 (1.3) 82.2 (2.7) 73.0 (4.3) 89.2 (0.9) 0.313 (0.207 to 0.412) on September 30, 2021 by guest. Protected copyright. by Spearman correlation coefficients ranging between 0.290 Table 6 presents VF/QOL data for the unoperated individu- and 0.447. The correlation was strongest for vision perception als. VF and QOL mean scores were generally higher in the and sensory adaptation subscales. Although generally not as unoperated than the cataract operated individuals with simi- pronounced, total QOL and QOL subscales also exhibited sig- lar vision status. Differences in total VF and QOL mean scores nificant correlations. The self care subscale was least affected for unoperated and operated individuals were compared using by diminished vision status. multiple regression, adjusted for presenting vision status and The 60–69 and 70–79 age groups had significantly higher demographic variables: adjusted VF and QOL total mean total VF and QOL scores than the 80 or above age group (for scores were found to be significantly higher in unoperated VF scores, adjusted p <0.001 and p = 0.050 respectively; for individuals (regression coefficient = 5.51, standard error = QOL scores, p <0.001 and p = 0.003 respectively). Housing 1.79, and p = 0.005 for VF scores; regression coefficient = type, sex, and education were not significantly related to either 4.24, standard error = 1.90, and p = 0.034 for QOL scores). total VF or total QOL scores (data not shown). Vision status and age were significant in the regression model. The mean total VF scores for aphakes and pseudophakes The other demographic control variables (housing, education, were 76.3 and 81.3, respectively, while the total QOL mean and sex) were not statistically significant. scores were 82.9 and 90.1, respectively. These differences in total VF/QOL scores between aphakes and pseudophakes were DISCUSSION not statistically significant when investigated by regression As a group, cataract operated eyes had reasonably good visual with adjustment for demographic variables and presenting acuity outcomes, with 59.6% having presenting visual acuity visual acuity status (regression coefficient = 0.16, standard of 6/18 or better. These results are clearly more favourable than error = 3.58, and p = 0.965 for VF scores; regression that found among rural Chinese populations in Shunyi6 and coefficient = 4.22, standard error = 4.72, and p = 0.380 for Doumen7 counties, where the percentage of operated eyes QOL scores). with presenting visual acuity of 6/18 or better was 25.0% and

www.bjophthalmol.com 16 Lau, Michon, Chan, et al Br J Ophthalmol: first published as 10.1136/bjo.86.1.12 on 1 January 2002. Downloaded from Table 6 Visual function and quality of life mean scores (and standard errors) by presenting vision status in unoperated individuals

Vision status

Moderate Severe Unilateral bilateral bilateral Normal blindness blindness blindness (n=87) (n=198) (n=25) (n=14)

VF scales Vision perception 92.9 (0.8) 77.3 (1.9) 61.7 (4.7) 54.2 (4.0) Peripheral vision 95.2 (1.1) 79.8 (2.1) 69.1 (6.2) 78.9 (6.2) Sensory adaptation 81.9 (2.4) 68.5 (1.5) 66.1 (3.7) 46.2 (6.4) Depth perception 97.7 (0.8) 85.6 (2.0) 81.9 (5.2) 70.9 (11.1) Total VF 91.9 (1.0) 77.8 (1.5) 69.7 (4.3) 62.5 (4.6) QOL scales Self care 98.4 (0.4) 87.5 (3.7) 94.2 (3.6) Mobility 91.7 (1.2) 72.3 (5.5) 76.6 (8.2) Social 87.0 (1.7) 77.0 (4.9) 55.6 (12.4) Mental 84.1 (1.9) 61.4 (5.5) 48.9 (8.3) Total QOL 90.3 (1.1) 74.6 (3.9) 68.8 (7.1)

23.7%, respectively. The percentage of cases that were pseudo- functions that involve visual discrimination and light percep- phakic, however, was much less: 39.7% in Shunyi and 5.9% in tion (visual perception and sensory adaptation) were more Doumen. The cataract surgery outcomes in Shatin are not as adversely affected. A similar pattern between visual function- favourable, however, as those obtained in a recent large scale ing and visual acuity status was found among Chinese clinical trial of cataract surgery in India, where 4 years after patients in the Doumen study.7 surgery 74.3% of pseudophakic eyes presented with visual Mobility, social interaction, and mental wellbeing among acuity >6/18, and 95.7% with best correction.13 14 Even with operated individuals were hampered by poor vision. Self care pinhole acuity,a large fraction of operated eyes in Shatin failed activities, such as bathing, eating, dressing, and toileting, were to attain visual acuity levels of 6/18 or better (27.9% of eyes not as affected. This is in contrast with the study conducted in failed) or 6/60 or better (9.3% failed). While many of these Shunyi, a rural county outside of Beijing, where all four qual- eyes had causes of visual loss unrelated to cataract surgery, ity of life subscales showed more equal detriment with declin- consistency in cataract outcomes is an important goal and ing vision status.6 The relatively high quality of life regarding should be monitored by public health authorities. self care despite vision impairment in the Shatin population Although a substantial percentage of cataract operated eyes may be explained, in part, by the small living space (mean size with subnormal presenting visual acuity showed improve- about 50 m2) among apartment dwellers, which makes self ment when measured by pinhole, pinhole correction still care activities comparatively more accessible. The availability underestimates the best possible corrected visual acuity. With of modern household utilities in Shatin, such as telephone, http://bjo.bmj.com/ refractive correction operated eyes could be improved even indoor plumbing, automated hot water, and gas, also may beyond that associated with the reported pinhole corrected make self care activities easier for people with poor vision. level. More attention should be given to ensuring that the Comparing the self reported visual functioning and quality implanted intraocular lens is of appropriate power and that of life scores between unoperated and operated individuals cataract operated individuals have suitable corrective lenses within the same vision category provides another assessment when necessary. Posterior capsule opacity (PCO) was another of the quality of cataract operations in Hong Kong. Cataract important remediable cause of vision impairment in cataract surgery can be considered successful if the operation restores on September 30, 2021 by guest. Protected copyright. operated eyes, affecting 8.4% of eyes with presenting visual the visual functioning and vision related quality of life in acuity <6/18. Together, refractive error and PCO accounted for cataract patients to levels similar to that among unoperated 43.0% of impaired eyes. individuals with similar vision status. Although the adjusted Recent and more temporally remote surgery did not show scores of operated individuals were somewhat lower than significant differences in terms of visual acuity outcomes. those of unoperated individuals, the differences were quite Pseudophakic eyes also showed no significant advantage over small. Although the differences were statistically significant, aphakic eyes in achieving presenting visual acuity of 6/18 or they may not be significant from a practical standpoint. greater, when adjusted for demographic variables. Private Because the study subjects were a randomly selected, popu- hospitals/practitioners showed a marginally significant ad- lation based sample, the findings presented here are thought vantage over public hospitals in postoperative visual out- to be representative of cataract surgery outcomes in Shatin, comes. Findings such as these must be interpreted with con- and possibly Hong Kong in general. Although the large sample siderable caution, as is the case with all observational studies. size allowed for investigating factors associated with surgical In the absence of randomisation, comparisons can be seriously outcomes using regression analyses, as was noted above cau- confounded by unrecognised factors. For example, pre- tion must be exercised in attributing a cause and effect existing ocular conditions before cataract surgery might have relation to any predictive factor. The main source of potential varied between groups along with other factors, such as the bias in this study was the modest examination response rate patients’ economic status, which may have been only partially of 76.7%, a rate low enough to allow for significant participant controlled for by the inclusion of housing type in the self selection biases. This was evidenced by the unexpectedly regression analysis. high proportion (69%) of cataract operated cases which were Visual functioning and vision related quality of life of the female. cataract operated population was positively associated with In conclusion, cataract outcomes in the Shatin area of Hong visual acuity. Visual functions that involve the perception of Kong can be substantially improved, with emphasis given to space and distance (that is, peripheral vision and depth postoperative visual rehabilitation as well. In the majority of perception) were least affected by impaired vision. Visual cases, simple refraction or posterior capsule opacity lysis could

www.bjophthalmol.com Visual acuity and quality of life outcomes in cataract surgery patients in Hong Kong 17

improve visual status. A programme of monitoring of cataract REFERENCES Br J Ophthalmol: first published as 10.1136/bjo.86.1.12 on 1 January 2002. Downloaded from outcomes would be useful to ensure continuous improvement 1 Michon JJ, Lau J, Chan WS, et al. Prevalence of visual impairment, in quality. With an ageing population, the need for vision blindness, and cataract surgery in the Hong Kong elderly. Br J Ophthalmol 2002;86:(in press). function and quality of life restoring cataract surgery will only 2 Zhao J, Jia L, Sui R, et al. Prevalence of blindness and cataract surgery increase. in Shunyi County, China. Am J Ophthalmol 1998;126:506–14. 3 Li S,XuJ,HeM,et al. A survey of blindness and cataract surgery in Doumen County, China. Ophthalmology 1999;106:1602–8. ACKNOWLEDGEMENTS 4 Hirvelä H, Luukinen H, Laatikainen L. Prevalence and risk factors of lens The authors wish to thank Dr Mark Tso, former chairman of the opacities in the elderly in Finland: a population-based study. Department of Ophthalmology and Visual Sciences, the Chinese Uni- Ophthalmology 1995;102:108–17. 5 Leske MC, Chylack LT Jr, Wu S-Y. The Lens Opacities Case-Control versity of Hong Kong, and the Shatin District Board for assistance in Study: risk factors for cataract. Arch Ophthalmol 1991;109:244–51. organising the research. Special thanks are given to Dr Bjorn Thylefors 6 Zhao J, Sui R, Jia L, et al. Visual acuity and quality of life outcomes in and Dr Dominique Negrel, World Health Organization, Dr G-P patients with cataract in Shunyi County, China. Am J Ophthalmol Pokharel, Foundation Eye Care Himalaya, Mr R D Thulasiraj, Aravind 1998;126:515–23. Eye Hospital, and Dr Astrid Fletcher, London School of Hygiene, who 7 He M,XuJ,LiS,et al. Visual acuity and quality of life in cataract patients in Doumen County, China. Ophthalmology 1999;106:1609– along with one of the authors (LBE), served on an external technical 15. committee that provided advice regarding study design and data 8 Natchiar GN, Thulasiraj RD, Negrel AD, et al. The Madurai intraocular analysis. Edmond Ng and Mason Lau, Centre for Clinical Trials and lens study I: a randomized clinical trial comparing complications and Epidemiological Research, assisted with data collection and analysis. vision outcomes of intracapsular cataract extraction with extracapsular cataract extraction with posterior chamber intraocular lens. Am J This research was supported by the World Health Organization, Ophthalmol 1998;25:1–13. National Institutes of Health Contract N01-EY-2103, and by a grant 9 Fletcher A, Vijaykumar V, Selvaraj S, et al. The Madurai intraocular lens from the Lions Club International Foundation. study. III: Visual functioning and quality of life outcomes. Am J Ophthalmol 1998;125:26–35. 10 Pokharel GP, Selvaraj S, Ellwein LB. Visual functioning and quality of ...... life outcomes among cataract operated and unoperated blind Authors’ affiliations populations in Nepal. Br J Ophthalmol 1998;82:606–10. J Lau, W-S Chan, Centre for Clinical Trials and Epidemiological 11 StataCorp. Stata statistical software: Release 6.0. College Station, Texas: Stata Corporation, 1999. Research, The Chinese University of Hong Kong, Hong Kong 12 Glynn RJ, Rosner B. Accounting for the correlation between fellow eyes J J Michon,* Department of Ophthalmology and Visual Sciences, The in regression analysis. Arch Ophthalmol 1992;110:381–7. Chinese University of Hong Kong, Hong Kong 13 Prajna NV, Chandrakanth KS, Kim R, et al. The Madurai intraocular lens L B Ellwein, National Eye Institute, National Institutes of Health study II: Clinical outcomes. Am J Ophthalmol 1998;125:14–25. 14 Prajna NV, Ellwein LB, Selvaraj S, et al. The Madurai intraocular lens *Current address: Department of Ophthalmology, Stanford University study IV: Posterior capsule opacification. Am J Ophthalmol School of Medicine, Stanford, California, USA 2000;130:304–9.

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